Electric controller.



A. C. EASTWOOD. ELECTRIC GONTROLL'ER.

V APPLIOATION FILED SEPT. 24, 1910 r 981,848. I Patented Jan. 17, 1911.

WITNESSES mvemn its off-position, that'is,

' UNITED STATES I ATENT OFFICE.

ARTHUR C. vE AS'IVVOOIJ, OF CLEJ ELAND, OHIO, ASSIGNOR TO THE ELECTRICCON TROLLER AND MANUFACTURING COMPANY. OF CLEVELAND, OHIO, A CORPORATIONOF OHIO.

which the following is a specification.

My invention relates to electric motor controllers of that type in whichseparately actuated magnetic switches are used tomake the properconnections for startin the motor, operate it indifferent directions,and vary its speed. It sometimes occurs in the operation of suchcontrollers that'when the master controller is moved to the OE positionsome one of the resistance cut-out switches may remain closed due to aheavy are which has been formed" at its contacts which welds themtogether.

The objectof my invention is to provide a controller in which it will beimpossible to operate the main switch or reverser 111 case any of theresistance cut-out switches number of ways, one of which is showndiagrammatically in the accompanying drawing.

I have shown a system of motor control in which the reverser ormainswitches are interlocked or prevented from operation by the action of apair of resistances 1* and Nassociated with the common return of there-' wiser-operating,coils. These resistances are connected in series,one end being I connected to the negative main; the other-end, to theleft hand or negative end of the starting resistance R; and apoint'between them, to a point between the negative terminals of thewindings of reversing switches 5 and '6, whose positive terminals areconnected to the respective contact strips m and n on opposite sides ofthe controller handle 0. The pdsitive contact strip m being arranged toengage the controller arm on either side of when the said arm contactswith the stri m orn.

If the master-switc arm 0 be moved to the'left to the first positionindicated 'by the first diagonal line on and m and closes a-circuit fromthe positive strip m through the arm '0, segment m, therev'erser-operatingpoiLfi land the resistance r to the negative mania"The current in this circuit causes the switch 6 to close its upper andlower contacts, but no the controlle'rM, it connects the contact stripsor segments m- ELECTRIC CONTROLLER.

v Specification of Letters Patent. Patented J 3.1 1'7, 1911, Applicationfiledfieptember 24, 1910. Serial No. 583,535.

current flows through the motor circuit as the arm 0 has not engaged anyof the segments m to m5; which are connected, respectively, to theoperating coils 1 to t of the "resistance-controlling switches l to t.If

now the arm 0 be moved so as to be in the second position to the left,itwill engage the segment m and close a circuit from the segment m, thearm 0, the segment m and the coil l -to thevne ative main, causing theswitch 1 to close t e motor' circuit which is as follows: from thepositive main through the switch 1, the entire resistance R, the

field F, the lower contacts of the switch 6,

the armature A, and-the upper contacts of the switch 6 to the negativemain. If the arm 0 he moved step by step so as to engage the segments mm, and m, the'coils 2 2, an 2 will be successively energized, whereu nthe switches 2, 3, and twill successively close, successivelyshort-ircuiting the sections of the resistance R in an obvious manner.If the arm 0 be moved to its ottosition, which is that shown'on thedrawing, all theco'ils 1, 2 3*, t steful 6 are deenergized, and theresistance switches 1 to 4 and the reversing switch 6 should open theircontacts; but in case one of the resistance switches, as 3, shouldremain closed and the arm o be moved so as to engage the segment m or n,a current would be set up from the positive segment at of the mastercontroller M through the reverser coil 5 orpi and the resistance 7" tothe nega-- A current also passes from the positive.

tive main through the closed resistance switch 3,,the third or lefthandsection of theresistanceR, and the resistances 1' and 1" in series tothe negative main. The coil 5 or 6 which is energized is thusconnectedin parallel with the resistance 1' the two parallel paths being inseries with the re; sistance 4 The resistance 1" is proportioned so asto permit suflicientcurrent to pass through one of. the reversing coilsto operate its switch when all the switches 1 to 4; are open. Since thetotal amount of current is limited by the resistance, 1", the

amount of current in the coil 5 or 5 is re-- ,duced when the saidcircuit including the resistance R remains closed. The resistances 2"and 1 should be so proportioned that, when the circuit through theresistance r is established, the current in the reverser coil 5 01"5 isnot sufficient to close its switch, but sufiicient therein to hold thisswitch closed after it has closed, it requiring, as is well known, asmaller current to maintain a magnetic switch closed than it requires toclose the same. It is thus seen that, in case any of the switches 1 to 4should remain closed after the reverser coils have been denergized andthe switches 5 and 6 in the energized reverser coil below a valuenecessary for closing its switch 5 or 6. It is impossible for eitherswitch 5 or 6 to be closed while any one or more of the switches 1 to 4are closed, but either switch 5 or 6 may be closed if all the switches 1to 4 are open. Besides securing this electrical interlock, my inventionhas the advantage of reducing the amount of current in the coil 5 or 6of the reverser as soon as the first'resistance switch is closed, whichis desirable to prevent the over-heating of the said coil. Theelectrical interlock is secured without the use of au'fziliary contactsand the reduction of current in the reverser coil is secured after theoperation of the first resistance switch without the use of auxiliarycontacts.

I claim I 1. In a circuit controlling system, a circuit, a resistancefor governing the current in said circuit, one or more switches for con:trolling said resistance, one terminal of each of said switchesconnected to one side of a source of supply, the other terminal beingconnected to said resistance, a second resistance, one end of which isconnected to said first resistance, the other end being connected to theother side of said source, a main switch for said circuit having anoperating winding, one terminal of which is connected at an intermediatepoint on said second resistance, and means for connecting the otherterminal of said winding to a source of supply.

2. In a circuit controlling system, a switch having an energizingwinding, means for connecting said winding to a source of currentsupply, a resistance in series with said winding, a second resistancewhich if connected 1n shunt with said winding will prevent the operationof said switch, and means for connecting said second resistance as ashunt around said winding when a second switch in said circuit isclosed.

3. The combination of a reverser, and a current varying controller,operating windings for. said reverser, and a shunt around said windingsfor preventing the operation of said reverser, said shunt being closedwhenever the current varying controller is in any position other thanthe o'lf 3 sition.

t. In a motor control system. a motor, a circuit therefor, a resistancein said'circuit, one or more resistance switches for controlling saidresistance, a reverser in said circuit, operating windings therefor, anda shunt around said windings which when energized prevents eitherwinding from operating the reverser, said shunt belng so connected as tobe operative whenever any of said resistance switches is closed.

5. Anelectric controller embracing a resistance, a series of switchesfor short-circuiting or reducing said resistance, an initial switchadapted to be closedby an electro magnet for closing the circuit throughsaid resistance, and means acting automatically, when any of saidresistance controlling switches is closed, for reducing the voltageapplied to the operating electromagnet of said initial switch to avoltage which will be i-nsuflicient to cause said initial switch toclose.

6. An electric controllerv embracing a resistance, a series of switchesfor short-circuiting or reducing said resistance, an initial switchadapted to be closed by an electromagnet for closing the circuit throughsaid resistanceyand means acting automatically, when an of saidresistance controlling switches is closed, for reducing the voltageapplied to the operating electro-magnet of said initial switch to avoltage which will be insufiicient to cause said initial switch toclose, said reduced voltage being sutiicient to maintain said initialswitch closed after it has closed.

7. In a motor control system, a motor. a circuit therefor, a resistancein said circuit,one or. more resistance switches for controlling saidresistance, a main switch or reverser in said circuit, operatingwindings therefor, a shunt around said windings closed whenever any ofsaid resistance switches is closed so that the closure of any of saidresistance switches serves to reduce the current which may flow throughsaid winding. 1

8. In a circuit controller, a magnetically operated switch forconnecting an electric circuit to one side of a source of currentsupply, and means for automatically reducing the voltage which may beapplied to the windingofsaid switch to prevent its operation wheneverthe circuit is connected at any point to the other side of the source ofsupply.

Signed at Cleveland, Ohio, this 19th day of September, A. D. 1910.

ARTHUR C. EASTWOOD. Witnesses: i

' J. H. HALL,

H. M. DI'EMER.

